It is known in the art to annotate or “mark” objects in a video stream with an interactive link. For example, suppose one was watching a video program of an automobile race, and there were several racing cars shown driving around a track. Also suppose that these cars were marked with interactive links. This means that one can position a cursor over the image of one of the cars and click on the image (or alternatively, click on special icons associated with the car). This causes the system controlling the video screen to take a predetermined action (e.g. execute a software program, or initiate some other event such as a telephone call) or display information that is linked to that image. This link can be in the form of a pop-up window for note annotation. (A pop-up window for note annotation is a small window that appears on the screen so that a user can write a small note. It is like an electronic “post-it” note.) Alternatively, the link can be in the form of a URL. If the link is invoked, the system will display a web page depicting information concerning the car or driver that has been clicked on. For example, the system can display details concerning the driver. As mentioned above, by clicking on the icon or image, one could also initiate an action, e.g. a telephone call to a merchandise company to buy a memorabilia product related to what has been clicked on.
During annotation, an area or region within the video frames surrounding the image of an object of interest (in the above-mentioned example, the racing car) is established as an “active area.” If one moves the cursor into the active area and clicks, one will initiate an action or invoke the link corresponding to the object within that active area. Typically, an object associated with the active area moves about the video screen during a video clip. For example, a video clip of an automobile race shows a group of cars moving about a racetrack, and these cars typically move about a television screen during the clip as the race proceeds. In such a video clip, a car might move from the right side of the video screen to the left side of the video screen. Thus, the active area must also move across the television screen to keep up with the object of interest. The above-incorporated patent applications pertain to methods for annotating video clips, i.e. defining the active area for each object of interest, and for each frame, in the video clip. These methods permit annotation with a reduced amount of human involvement in the process. It would, however, be desirable to further simplify the process of defining active areas in a video clip.